In development for a decade, NIST-F2 will be accurate over 300 million years.

Earlier this week, the National Institute of Standards and Technology (NIST) officially launched an atomic clock that is three times as accurate as the one used today to do everything from synchronize GPS systems to time-stamp financial transactions.

The previous atomic clock, called NIST-F1, was launched in 1999. It was accurate to within plus or minus one second over the course of 100 million years. The newly launched atomic clock, called NIST-F2, is accurate to within plus or minus one second over 300 million years.

Both clocks are based on a Cesium atom fountain. Physicists measure the frequency of a transition that the Cesium atoms make, which divides a second into 9,192,631,770 vibrations per second. NIST explains how the F2 standard is so much more accurate than the older standard:

The key operational difference is that F1 operates near room temperature (about 27 ºC or 80 ºF) whereas the atoms in F2 are shielded within a much colder environment (at minus 193 ºC, or minus 316 ºF). This cooling dramatically lowers the background radiation and thus reduces some of the very small measurement errors that must be corrected in NIST-F1.

EETimes also notes that smaller improvements to the Cesium fountain have been found by “including components that shrink and expand by as much as one centimeter, as the clock is cycled to and from very cold temperatures. Also the six lasers used to cool the cesium atoms have been optimized in a new configuration.”

NIST-F2 has been under development for a decade, but physicists working on the project say that no practical use for the more accurate clock has been found—yet. NIST expects that to change. "If we've learned anything in the last 60 years of building atomic clocks, we've learned that every time we build a better clock, somebody comes up with a use for it that you couldn't have foreseen," NIST physicist Steven Jefferts, lead designer of NIST-F2, was quoted as saying in a NIST press release.

The standards institute plans to operate both atomic clocks for now and use them for long term comparisons studies.